Miniaturized ceramic components, in particular, demonstrate an increasing drift of their electrical characteristics under the influence of moisture and/or water, which can result in total failure of the component if the effect of moisture continues. Studies have shown that this instability with regard to specific climate conditions is attributable to electromigration. Because of the voltage that is applied to the component, i.e., to electrodes of the component, when the component is in operation, a difference in potential exists between different electrical poles of the ceramic component. If conditions of use of the component are now such that a continuous moisture film can form between the electrodes, material transport of the electrode material from the anode to the cathode will result. The metals silver, tin, and lead, which are usually contained in the solder with which the electrical connectors are attached to the electrodes, are particularly affected by this electromigration. At the same time, the migration leads to the formation of metallic deposits on the path from the anode to the cathode, which can form continuous metallic films and tracks on the ceramic. As a result, resistance between the electrodes decreases dramatically, leading finally to short-circuiting and thereby to total failure of the ceramic component.
In the case of miniature ceramic components, which comprise, in the standard method of construction, a ceramic body with fired electrodes, soldered connector wires, and a plastic protective sheathing, a design that is reliably protected against electromigration, has not been known until now. Improved resistance to electromigration is achieved if epoxies modified to be hydrophobic are used as the plastic sheathing, as is described in older German patent application 198 51 869.2, which is not a prior publication. Glass-encapsulated sensors, in which the component is provided with a coating consisting of glass, represent a further improvement. However, high process temperatures are necessary to produce the glazing, so that no insulated connector wires can be used. Under climatically demanding conditions of use, damage caused by electrochemical corrosion of the connector wires and/or by migration over the glass body is observed here as well.